[ProgrammerMike7]

We had last years ADXL345, so we wired that up and it works fine. However, we encounter another problem when having the HiTechnic Compass plugged into the NXT I2C port at the same time the accelerometer is plugged into the spare I2C port. They both work and display values when they are plugged in alone, however when they are both plugged in together, neither will update values and display 0.000000. We do not get any errors, they simply do not work. We also checked the compass and accelerometer source code to make sure that the compass and accelerometer had different addresses which they do (Accelerometer is 0x3A, and compass is 0x02). Here is the code with the Compass added.

#include "WPILib.h"

class MyRobot : public IterativeRobot {
	
	HiTechnicCompass myCompass;
	ADXL345_I2C myAccel;
	DriverStationLCD *driverStation;

	double xAccel, yAccel;
        double compassAngle;

public:
	MyRobot():
		myCompass(4),
		myAccel(4, ADXL345_I2C::kRange_2G)
	{
		driverStation = DriverStationLCD::GetInstance();

	}

	void TeleopInit() {
		GetWatchdog().SetEnabled(true);
		GetWatchdog().SetExpiration(0.5);
		driverStation->Clear();	
	}

	void TeleopPeriodic() {
		
		while(IsOperatorControl() && IsEnabled()) {
			GetWatchdog().Feed();
			
			char xAccelChar[100];
			char yAccelChar[100];
			char compassChar[100];
			char testChar[100];
			
			xAccel =  myAccel.GetAcceleration(ADXL345_I2C::kAxis_X);
			yAccel =  myAccel.GetAcceleration(ADXL345_I2C::kAxis_Y);
			
			compassAngle = myCompass.GetAngle();
			
			sprintf(xAccelChar, "Accel X: %f", xAccel);
			sprintf(yAccelChar, "Accel Y: %f", yAccel);
			sprintf(compassChar, "Compass: %f", compassAngle);
			
			driverStation->Clear();
			driverStation->PrintfLine(DriverStationLCD::kUser_Line1, xAccelChar);
			driverStation->PrintfLine(DriverStationLCD::kUser_Line2, yAccelChar);
			driverStation->PrintfLine(DriverStationLCD::kUser_Line3, compassChar);
			driverStation->UpdateLCD();
		}
	}
};
START_ROBOT_CLASS(MyRobot);

We would appreciate any advice that could fix this issue.